Sound-absorbing structure



p 1953 J. MAZER SOUND-ABSORBING STRUCTURE v Filed Dec. 24. 1949 INVENTOR. ([4605 M4 202 BYW/ZM a I Patented Sept. 15, 1953 UNITED STATES PATENT OFFICE SOUND-ABSORBING STRUCTURE Jacob Mazer, Germantown, Pa.

Application'December 24, 1949, Serial No. 134,923

3 Claims.

This invention relates to sound-absorbing structures of thesame general type: as that shown in my application Serial No. 91,955, filed May 7, 1949, the present application being. directed primarily to various arrangements of sound-absorbing units not disclosed in the-said application.

In placing'sound-absorbing materials in rooms, against the ceiling or walls, attention has been directed primarily to the matter of securing sound-absorbing or sound-.quieting effects, with insufiicient consideration of the distribution of sound that is not absorbed. The'result has been that even though the reverberation period has been much reduced in ,a given room or enclosure and the acoustical effect materially improved thereby, in many cases, still greater acoustical improvement can be effected by controlled distribution or diffusion of the deflected sound. Even where there is substantial sound absorption, it is not unusual for one-half or more of the sound to be deflected from the sound-absorbing units and from the other surfaces of a room, and even more than one-half of the sounds of ,low frequencies are deflected, thus producing disturbing acoustical results.

Owing to this lack of controlled deflection, particularly from the higher-sound absorbing surfaces, parts of the audience such as that directly in front of the speaker or other sound source will hear the sounds with greater intensity than is necessary or comfortable, while those parts of the audience to the rear or at thesides of the room, will receive the sound with-insufiicient intensity, for comfort ,or-clarity.

My invention has for its object the provision of sound-absorbing structures or units thatacan readily be so arranged as to deflect and diffuse the unabsorbed sound to desired parts of a room, thus making for the more. even distribution and intensity of the audible sound.

Some of the forms which my invention may take are shownin the accompanying drawing,

wherein Figure 1 is a perspective view of a portion of a wall or ceiling equipped with my invention; Fig. 2 is an enlarged view of one of the strips or pieces employed in assembling theunit of Fig. 1; Fig. 3 is a perspectiveview of a portion of a wall or ceiling showing the modification of the structure of Fig. 1; Fig. 4 shows still another modification; Fig. 5 is av perspective View of a sound-absorbing unit having reflecting surfaces arranged on curved lines; Fig. 6 is an enlarged detailed view of one of the strip members of Fig. 5; Fig. 7 shows a modification of the structure of 'Fig. 5; Fig. 8 shows still another form of'the invention; Fig. 9 is a schematic view showing a manner in which various units may bearranged,

2 in assembled relationship, on a wall or ceiling; Fig. 'lo'shows another form of strip, and Fig. 11 shows a unit'formed of such. strips.

WhiIethe various units shown in the drawing show .the units as being built up of strips and having grooves and holes therein of predetermined number, spacing. size and shape to increase sound absorption, as shown in my said application, it will be "understood that various features of the invention and particularly the curved orangular disposition of the faces of the units is of advantage inthe controlled deflection of sound waveseven though'the units were made in the form of large or small single-piece slabs orsheets of other types of sound-absorbing materia Referring first to Figs. 1 and 2, I show a plurality of units H-applied to a wall or ceiling l2 and each-composed of strips l3 that may suitably be formed of fibrous material after the manner of well-known fiber boards or more loosely compacted fibrous strips, or of other porous material of desired density or compactness. Thestrips 13 of each unit II can be secured together by cementing or wiring as in Fig. 501- can simply be cemented to the wall [2. As in my said application, the sides of the strips l3 are grooved, so that when they are assembled,

' there will be circular or-othershaped holes I4 with consequent better hearing.

be cemented or nailed .to the wall or ceiling .or

even suspended outof contact with the wall or ceiling.

It will be seen that the sloping faces of the units ll reflect sound waves at different angles than if the unit faces were parallel to the plane of the wall l2. For example, if the units are placed on the rear wall of a room, wherein the sound originates at the front of the room,the ,portionsofthesound waves that impinge upon -unitsand are not absorbed will be deflected in a generally downward direction toward the audience located inthe rear parts of the room, Somewhat the same effect will. be produced if the units are placed on a. ceiling or upper side walls. The slope of the faces would, of course, be disposed in such manner as to deflectsound waves either laterally In Fig. 3, I show units I5 similar to the units H, but wherein the butt ends or thick ends of the units are placed in engagement with one another at 16. This gives a wave-like effect whether. the faces of the units are curved or have flat In Fig. 4, I show an arrangement whereby the units I1 may be of uniform thickness and still. so arranged as to effect desired angular deflec tions, as distinguished from the deflections less; widely distributed and of larger wave-front, such: as occurs when the faces of the units are parallel to the wall or ceiling I8. Here again, the units can be turned in various directions on a wall or ceiling, and the arrangement has the further fea-' ture of providing spaces between l8 and the units, resulting in increased sound absorption values, especially for the sounds of low frequencies.

Referring now to Figs. 5 and 6, I show strips 2| of the form disclosed in Fig. 4 of my prior application, with particular reference to thewave-line contour of the outer edges or faces of the strips. The deflecting and diffusing effect of the units of this character is similar to that of Fig. 3, wherein each unit has controlled deflection of sound waves in a plurality of directions. The strips of Fig. 5, as in the case of the other units, can be glued together or held together by wire lacing as at 22.

In Fig. 7, I show a unit 23 which is composed of strips arranged similarly to those of Fig. 5, but wherein the convex and concave areas of each strip are staggered relative to the concave and convex areas of the adjacent strips. There is, therefore, not only the deflection of sound waves by the curved areas, but there is multiple deflection between the protuberant or convex areas of alternate strips. Thus convex surfaces of a strip 23a are disposed alongside of the concave sur faces of a strip 23b and in opposed relation to the convex or protuberant surfaces of a strip 230, and so forth across the unit. Sound waves are repeatedly deflected back and forth between these raised surfaces, thus increasing both the ab sorption and the diffusion of the sound.

In Fig. 8, I show another arrangement, wherein there is a space 25 behind the face of a soundabsorbing unit 26 that may suitably be made of strips secured together in unitary relation and wherein the marginal strips 21 are of greater depth than the other strips, so as to provide for the spacing at 25. Holes 28 may lead into the space, but the space is acoustically effective with or without the holes.

Fig. 9 shows a mosiac-like arrangement into which various of the units may be placed not only to give a pleasing architectural effect, but also to deflect sound waves at an increased multitude of angles.

In Fig. 10, I show a form of strip 30 which differs from those shown in the various other figures, in that its sides that are perpendicular to the wall are of irregular contour, so that when the strips are assembled as shown in Fig, 11, there will be a number of apertures 3| of uneven shape that serve as sound-absorbing openings, it

4 being understood, of course, that there will be sound dissipation or absorption between the op posed walls of these strips throughout substantially the entire length of the strips, even where the strips have some direct engagement with one another at areas between the openings 3|. Some of the depressions at 3| in one strip are not directly opposite to depressions in the other strip. A similar staggered arrangement could be made in the case of the smooth round holes or grooves of the other units, so that the one-half grooves in each strip would not necessarily be directly opposite to the half-grooves of the adjoining strips.

jReferring further to the various advantages of having slabs of non-uniform thickness as in Figs. 1, 3, 5, 7 and 8, the thickness of a sound-absorbing unit, whether of the perforate or imperforate type, is of some consequence, because increasing the thickness of a unit, results in a general increase in its absorption capacity, particularly at the lower frequencies, such as 128 and 256. Generally, the ideal material would be one that has the same efficiency at all frequencies, but since this is not possible, I obtain a better average of absorption coeflicients by providing slabs or units of different thickness at various of its areas. The stepped arrangement of Fig. 4 produces a general average effect somewhat similar to the use of slabs of non-uniform thickness.

As stated heretofore, the units can be made up in the form of single slabs instead of assembled strips and may be of various materials other than the fibrous materials referred to. Also, the sloping and curved surfaces are of utility aside from the inherent sound-absorbing capacity of the unit, since such surfaces will give controlled reflection of sound waves.

It will be understood that the term wall is used in a broad sense, and that it is contemplated the units shall be applied to walls, ceilings, columns, or even mounted in spaced relation to such surfaces.

I claim as my invention:

1. A sound-absorbing structure comprising slabs of fibrous sound-absorbing material, each formed of fibrous strips assembled in side-by-side abutting relation for the entry of sound waves between them and the strips having grooves that extend rearwardly from the faces of the slabs, along the opposing faces of the strips.

2. A sound-absorbing structure as recited in claim 1, wherein some of the strips extend rearwardly a lesser distance than adjacent strips.

3. A sound-absorbing structure as recited in claim 1, wherein some of the strips are of wavelike contour on their outer surfaces.

JACOB MAZER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,554,180 Trader Sept. 15, 1925 1,825,770 Barnett Oct. 6, 1931 1,875,074 Mason Aug. 30, 1932 2,057,701 Stranahan Oct. 13, 1936 2,410,413 Hurley Nov. 5, 1946 FOREIGN PATENTS Number Country Date 107,975 Australia 1938 504,795 Great Britain 1939 510,522 Great Britain July 31, 1939 572,576 Great Britain Oct. 15, 1945 

